Process for coating roofing felt



May 2l, l929- -.J. c. BLACK ET AL. 1,714.206

v PROCESS FOR COATING ROOFING FELT Filed March'lO, 1927 INVENToRs required melting point and consistency has Patented May 21, 1929.

UNITED STATES PATENT OFFICE.

JOHN C. BLACK, WIRT D. RIAL, OF LOS ANGELES, CALIFORNIA, ASSIGNORS T0 PAN AMERICAN PETROLEUM COMPANY, 0F. LOS ANGELES, CALIFORNIA, A COR- PORATION OF CALIFORNIA.

PROCESS FOR COATING ROOFING FELT.

Application led MarchilO, 1927. Serial No. 174,370.

This invention relates to the manufacture of rooting material, and refers particularly to that step in the process of coating roofing -felt with a suitable asphaltic material, which has been subjected to heat and air until the been obtained.

The roofing felt to be coated, may be any material employed for such purposes, such asfelt, made from wood liber, waste paper, cotton or woolen rags, and. processed by any of the methods known in the art for the manufacture of felt or paper.

The as haltic material employed for coating the elt or paper may be any suitable asphaltic cement, manufactured by any preferred method from an asphalt or mixed base crude vpetroleum oil, or residuum having the required melting point and conslstency. or example, an air blown asphalt having the following tests may be employed.

Penetration at 77 F., 15 to 22.

Melting point, 210 to 235 F.

In the manufacture of roofing felt or paper, it is customary first to saturate the felt or paper with a low melting air treated asphaltic stock, which has a penetration of approximately 105 to 120 F. and a melting point of 105 to 115 F.; and thereafter' coatthe saturated felt or paper with a higher melting air treated asphaltic stock.

In the application of the oxidized, or air treated asphaltic stocks, which are usually applied to the paper or felt at temperatures of approximately 400 F., heretofore, considerable trouble has been experienced during this coating operation due to surface oxidation, whereby lumps of higher'melting asphaltic products are formed. These lumps of higher melting asphalt may stick to the paper or felt. producing thereby a rough and uneven coating.

We have discovered that these ditliculties can be overcome and auniform liquid maintained, without the formation of lumps during the coating operation, by displacing the air and maintaining in the container in the space above the melted asphalt an inert' gas such as carbon dioxide, nitrogen, or a. hydrocarbon gas, and the like, preferably a mixture of nitrogen, carbon dioxide, which may be obtained by the ignition of air and a hy drocarbon gas or oil.

Various further features of the present invention will be understood from a description of a preferred-form or example of a process embodying the invention. For this f dome 4 through which the asphalt or coater stock may be charged into the tank 1. Conf nected totank 1 at the top isa pipe 7 which leads .to a vacuum and pr'essure regulating valves 5 and 6, by means of which a constant pressure may be maintained on the system. 9 indicates a combustion chamber filled with checker brick work 10, with space 12 at the bottom, into which are fed gas and air through the pipes 13 and 14 in proportion suitable for making a substantially complete conversion of the oxygen content into oxides of carbon. 15 indicates a blower which discharges into pipe 14, which is provided with an oriiice plate 16 so that a regulated iow of air may be maintained. f

In like manner 20 is a blower which` discharges a hydrocarbon gas into the` pipe 13, which is provided with an orifice plate 19 so that a regulated constant flow of a hydrocarbon gas may be maintained.

8 indicates a pipe connected to the tank 1 and leading into a gas holder 21 for holding a supply of the nonoxidizing gas. Connected to the pipe 8 is a branch pipe 22 an open which is connected tothe combustion chami ber 9 at the top, by means of which the nonoxidizing gas may be conducted into the gas holder 21, or into t-he vtop of tank 1.

23 is a pipe, connected to the bottom of tank 1, controlled by a valve 24 and leading 27 which leads to the suction side of a pump 30. Pump 30 discharges into pipe 31 which is connected to and leads to the bottom of tank 1. I

32, 33, 34, 35, 36 and 37 are rollers which conduct the saturated felt or paper yinto the coater tank 24', where said paper receives Acement manufactured by any preferred method, such as an air blown asphalt having a lmelting point of approximately 220 F., is

introduced into the tank'l through the man hole 4, either in a liquid or solid state, by connections not shown. Heat is then applied to tank 1 by means of the burner 3 in the furnace 2 until the coater stock has attained a molten condition at the desired temperature, approximately 400 F. At the same time a non-combustible gas is introduced into said tank 1 through the pipe 8 which leads to the gas holder 21, the gas holder 21 having been filled with a non-combustible gas before the tank 1 is charged with the coater stock. During the introduction of the non-combustible gas into tank 1, the air contained therein is permitted to escape through the safety valves 5 or 6. v

The method employed for filling the gas holder 21 is as follows. Air coming through pipe 17 passes into the suction side of blower 15 and is discharged into pi e 14, passing through orifice plate 16. At t e same time a hydrocarbon gas is introduced into the said `combustion chamber 9 from a source not shown, passing through pipe 18 and into the suction side of blower 20 which discharges through orifice plate 19 passing in a regulated flow into said combustion chamber 9. The hydrocarbon gas and air passing into said combustion chamber is ignited and permitted to burn during thefilling of the gas holder 21.

The mixture of air and hydrocarbon gas is so regulated that a complete combustion will beeii'ected With a slight excess of the hydrocarbon gas during the passage of said mixture of said hydrocarbon gas and air through the checker brick work 10. The products of combustion, consisting principally of nitrogen,

carbon dioxide, and a small percentage of hydrocarbon gas, pass from the combustion vchamber 9 through pipe 22 and then into the p1pe8 which leads into the gas holder 21, or

the gas may pass directly through the pipe 8 and into the top of thetank 1.- AIf itsis so desired a hydrocarbon gas alone may be employed, in which case the gas holder would be filled with a ,suitable hydrocarbon gas without any admixture and combustion with air. Also it is to be understood that the gas holder 21 may be filled with any other non-combustible gas such as carbon dioxide, or a hydrocarbon gas coming from the heating of the coater stock contained in tank 1. The vacuum and pressure regulating valves 5 and 6 may be set for any convenient pressure or vacuum, usually a pressure of from 1 to 5 pounds is sufficient, a vacuum safety valve being employed only for safety in case the gases contained in. tank ly and gas holder 21 should be suddenly cooled and contracted.

It is to be understood that gas holder 21 acts as a storage and regulator for the system, the non-oxidizing gas passing into tank 1 and equalizing the pressure as the asphalt contained therein is used and the level lowered, also that when tank 1 is charged again and the level of the asphalt content is raised a part of the non-oxidizing gas passes back into said gas holder 21 thereby equalizing the pressure. The combustion chamber 9 is employed only to make up the loss ofA the nonoxidizing gas. i

The hot coater stock is conducted in quantities suiiicient into the coater tank 24 and at the same time a circulation is maintained throughout the system in order to keep the coater stock at the desired uniform temperature by means of pipe 26 regulating valves 28 and 29 so that a portion of the ow from tank 1 will not pass through the coater tank 24', valve 25 being regulated so that a constant height of the coater stock and the required temperature will be maintained in the said coater tank 24.

The paper or felt to be coated coming from a source not shown passes over the rolls 32, 33, 34 and 35, and then dips into the coater stock contained in the coater tank 24', passing over the two rolls 36 and 37. From the roll 37 the coated felt passes through a set of rolls 38 which compresses the coated paper and thereby any excess of coater stock falls back into the coater tank. From the rolls 38 the paper passes over rolls, 39 and 40 and then to other processing well known in the art.

While the process herein described is well adapted for carrying out the objects of the present invention, various modifications and changes may be made without departin from the invention and the invention includes all such modifications and changes as come Within the scope of the appended claims.

We claim:

1. The process of coating roofing felt or paper, which consists in maintaining a body of melted asphalt contained in a closed receptacle, and preventing any substantial oxidation of said melted asphalt by dis lacing the air contained therein, by the mtr uction of a non-oxidizing gas, maintaining said asphaltat a constant temperature of approximately 400 F. by heating and circulating said melted asphalt through a closed 'pipe and employing said heated melted asphalt to coat roofing felt or paper by introducing.

regulated quantities of said circulating asphalt into a coater tank to maintain a constant level therein; through which the paper or felt is passed and coated with said'asphalt.

2. In the process of preparing air-blown asphalt for use in coating roofing;r felt or the' like, the step which comprises ofnieltingr the.

air-blown asphalt in an atmosphere of an inert gas thereby preventing further oxidation of the asphalt. c v

3. In the process of preparing air-blown asphalt for use in coating roofing felt, the step which comprises of maintaining a body of molten air-blown asphalt at a temperature of about 400 F. in an inert non-oxiclizing at'- -Which comprises coating the' felt with molten air-blown asphalty maintained, as a 'molten mass prior to use, in an inert atmosphere.

5. .In the process of coating roofing felt and the like with air-blown asphalt, the step which comprises coating the felt with molten air-blown asphalt maintained, as a molten mass prior to use, in an inert atmosphere and at a, temperature of about 400 F.

In testimony whereof we aix .our signatures.

'JOHN C. BLACK. WIRT D. RIAL. 

